Mold for making a sound producing article



Dec. 24, 1957 T. A. MILLER ET AL MOLD FOR MAKING A SOUND PRODUCING ARTICLE Filed April 8, 1955 llllll I l l n H l l l (91%.;- 'mreul United States Patent 2,817,116 Patented Dec. 24, 1957 fine MOLD FOR MAKING A SOUND PRODUCING ARTICLE Theodore A. Miller and Theodore A. Miller, Jr., Cuyahoga Falls, Ohio Application April 8, 1955, Serial No. 500,214

2 Claims. (CI. 1839) This invention relates to a mold for making sound producing articles particularly to hollow flexible plastic articles producing a whistling sound.

Heretofor it has been the practice to provide hollow flexible toys, such as balls, doll-s, toy animals, and toy blocks with whistles for providing a sound when the article was squeeze-d. Such whistles have usually been made of metal or other rigid material and have been inserted in openings in the article.

While such inserted whistles have provided a satisfactory sound, they have been dangerous in the hands of infants as they might be loosened and swallowed by the infant. Such whistles have also been expensive to manufacture and to assemble with the toy.

It is an object of the present invention to overcome the foregoing and other diificulties by forming the toy and a whistle integral therewith and of the same material.

Other objects are to provide a mold for making a toy which is safe in the hands of infants, to reduce the cost of such toys, and to provide for simultaneous molding of the toy and its whistle.

These and other objects will appear from the following description and the accompanying drawings.

Of the drawings:

Fig. l is a vertical elevation, partly broken away and in central vertical section of a toy block constructed in accordance with and embodying the invention,

Fig. 2 is a plan view of a mold for a toy block such as that of Fig. 1,

Fig. 3 is a cross sectional view of the mold of Fig. 2 taken on line 33' of Fig. 2.

Referring to the drawings and first to Fig. 1 thereof, the numeral designates a hollow cubical toy block of flexible plastic material having an end wall 11 in the center of which is an aperture 12. The aperture 12 is round in cross section and extends from the outer surface of the block a distance substantially equal to the thickness of the wall 11 and connects with an oblate spheroidal cavity 13 which in turn is connected to the interior cavity 14 of the block by a conical passage 15 which increases in diameter toward the interior of the block. The cavity 14 and conical passage 15 intersect in a sharp annular ridge 16 of diameter slightly larger than the passage 12. The cavity 14 and passage 15 are surrounded by a wall 17 of material substantially equal in thickness to the wall 11 and merging therewith. The arrangement is such that the passages 12 and 15 and cavity 13 with the surrounding wall 17 provide a whistle integral with the block and adapted to provide a sound when air is forced through the passages as by squeezing the block.

The block 10 is formed by deposit of plastic material on the walls of a closed mold from a dispersion of plastic material by gelling and thermosetting of the material, and for this purpose molds, such as the mold shown in Figs. 2 and 3 are provided and mounted between spider plates of a molding machine whereby the molds may be clamped in closed condition and may be rotated about a plurality of axes while they are progressively passed through a heating oven and a cooling chamber.

The molds comprise a box-like cavity member 20 having a cubical cavity 21 formed therein and closed by a cover 22, the mold and cover having stepped margins 23 fitting one another to center the cover and provide a tight joint.

For forming the whistle the cover 22 is provided at its center with a core pin 24 projecting inwardly of the cavity. The core pin has a stem 25, of a diameter adapted to form the bore 12 of the toy, whereby the core pin is mounted in a bore 26 of the cover. The stem 25 is a press fit in the bore 26 and a hole 27 of reduced size is provided through the cover in alignment to the bore 26 for reception of adrift pin when the core pin is to be removed.

The core pin has an oblate spheroidal enlargement 28 spaced from the wall of the cavity 21 to form the cavity 13 and terminates in a conical enlargement 29 having its greater diameter inwardly of the mold cavity. The innermost end of the core pin is formed with a concave face 30 which meets the conical surface 29 in a sharp peripheral self-trimming edge 31.

The core pin 24 is preferably made of strong noncorrodible material such as stainless steel as such material provides a smooth clean surface and takes a sharp edge.

In use of the mold, a quantity of dispersion of plastic material such as plastisol is placed in the cavity and the mold closed. The mold is then rotated about a plurality of axes while passing through a heated oven to gell and thermoset the material on the cavity walls. The material deposits all over the core pin 24 but the pin is so proportioned that the sharp edge 31 is barely covered by the deposit which extends across the concave face 30, thereby providing a self-trimming peripheral line at the end of the core pin. Obviously the wall thickness of the resulting article will depend upon the quantity of pl astisol placed in the mold cavity and this amount is accurately measured. Also the dimensions of the core pin should be such that such a thickness of wall will provide substantially a thin film only across the self-trimming edge 31. Furthermore, the sound provided by the whistle has been found to depend upon the wall thickness of the article about the whistle cavity and especially in the resultant bracing of the wall about the aperture 12 and cavity 13 it being desirable to have a thickening of wall where the wall about the cavity 13 joins the wall 11. For adjusting the thickness of deposit at this location, the core pin may be moved axially to adjust the space between the wall 21 of the cavity and the enlargement 28 of the core pin. This distance for best results has been found to substantially equal the wall thickness 11 of the article. When the spacing is too great, the sound produced is weak.

In forming the article, a disc-like deposit of material is formed over the concave face and barely covers the trimming edge 31. After the article is thermoset, the mold is opened and the article tends to cling to the core pin 24 reducing the air pressure within the article. As the core pin is drawn from the article, air rushes in and breaks loose the deposit over the end of the core pin. The deposit, in the form of a disc is blown into the article and remains therein or may be forced out of the article by squeezing the article to compress the air therein.

The self-trimming edge 31 greatly facilitates the manufacture of the article as it eliminates trimming. The provision of the integral whistle reduces the cost of manufacture of the toy and by eliminating in secure separate whistles, provides a safe toy.

While the invention has been described in connection with a toy block article, it is to be understood that articles of other shapes may be provided with whistles integral with the article by following the same procedure and that the invention is not confined to an article of a single shape.

These and other modifications may be made without departing from the scope of the invention as it is defined by the following claims.

.I claim:

1. A mold for forming a hollow article having a whistle integral therewith by thermosetting therein of a dispersion of plastic material, said mold comprising mold members defining one with another a closed cavity therebetween, and a core pin mounted on one of said members and extending into said cavity for forming said whistle, said core pin having a bulbous enlargement spaced inwardly of the mold wall and having therebeyond an outwardly flared conical portion of greater diameter than its length and terminating in a concave end defining with the conical surface of thin sharp peripheral cutting edge at the inner end of the pin.

.2. .A mold for forming a hollow article having a whistle integral therewith by thermosetting therein of a dispersion of plastic material, :said mold comprising mold members together defining a closed cavity therebetween, and a core pin mounted on one of said :members and extending into said cavity for a distance no greater than the thickness desired at said whistle, said core pin comprising a bulbous portion spaced from the inner surface of the mold by the desired wall thickness of the whistle for forming a resonant cavity, and an outwardly flared conical portion of length equal to the desired Wall thickness of the whistle directly adjacent the bulbous portion and having a diameter at its larger end greater than its length, said pin terminating in a concave surface'atthe base of the conical portion and defining with the conical surface a thin sharp peripheral cutting edge of acute cross section.

References Cited in the file of this patent UNITED STATES PATENTS 259,984 Hyatt et al. June 20, 1882 1,564,310 Jones Dec. 8, 1925 2,100,575 Spanel Nov. 30, 1937 2,209,877 Ferngren July 30, 1940 2,661,498 Blaurock Dec. 8, 1953 2,717,473 Moore Sept. 13, 1955 2,721,420 Chatten Oct. 25, 1955 2,730,765 Crafton et al. Jan. 17, 1956 

